This invention relates to magnesium reduced titanium tetrahalide catalyst systems.
It is known to utilize true Grignard reagents of the formula RMgX prepared in the presence of an ether to reduce titanium tetrahalide in the production of catalysts. It is also known to produce what is termed in the art a "solventless" Grignard, which is produced by reacting magnesium metal with an organic halide in the presence of a solvent which is designated as a non-solvating solvent (i.e., an inert non-complexing diluent) such as a hydrocarbon as ditinguished from an ether. This use of true Grignard reagents presents serious difficulties, however, in the production of certain catalysts, particularly in the production of olefin polymerization catalysts, in view of the fact that the large amount of ether is difficult to remove and the remaining complexed ether can reduce the effectiveness of olefin polymer catalysts systems prepared with the thus treated Grignard reagents.
Because of greater process economics, it is desirable to carry out olefin polymerization reactions, particularly polymerization reactions involving ethylene and predominantly ethylene copolymers, and an inert diluent at a temperature at which the resulting polymer does not go into solution, with the polymer being recovered without elaborate steps to remove the catalyst. In order for this more economical method of manufacture to be feasible from a practical standpoint the catalyst must be capable of producing polymer in high productivities in order to maintain the residual catalyst level in the final polymer at a very low level.